In an image forming apparatus, such as a laser printer, a laser beam is swept, or scanned, across a photosensitive device. The accurate and precise placement of the swept laser beam ensures that the resulting output from the image forming apparatus is an accurate representation of the desired image.
It is also desirable to accurately control laser beam intensity, and one technique for doing so is found in U.S. Pat. No. 5,264,871, titled “Image forming apparatus having light beam intensity switching for detection purposes,” issued to Tsukada on Nov. 23, 1993. It discloses an image forming device with a beam detect sensor 31 that provides timing and position information for the laser beam 7. The Tsukada patent addresses the problem in which the laser power is changed to correspond with a selected pixel density and that same laser power level is used by the beam detect sensor 31. The Tsukada patent discloses an apparatus for switching the laser beam intensity to correspond to a position of a pixel density selection switch.